These packings are used to form a seal between two cooperating parts of a hydraulic apparatus, primarily faucets and cartridges for faucets. The cup packing is inserted in a seat that is recessed in one of the two parts between which a seal must be established, and it is forced into contact with the other part. The force is often applied by a spring housed inside the cup packing, but it can also be applied by means of diverse or diversely arranged members or by the elasticity of the elastomeric material comprising the cup packing. To establish the best possible hydraulic seal these packings should be made of an elastomeric material that has a high degree of elastic yield. As a rule, conventional cup packings have a circular cross-section.
The conventional and known cup packings have serious disadvantages. For both technical and regulatory reasons hydraulic apparatus must be able to resist high pressures which, according to some standards, attain 50 bar and even 120 bar. If the cup packings are comprised of elastomeric material under high pressures, and especially in the case of pressure surges, they can become deformed and can even burst. This means that such packings must be made with relatively rigid elastomeric material which is unable to establish the best possible seal. This phenomenon is also present when the packings are installed under operationally static conditions.
When such packings are used under operationally dynamic conditions, i.e., when they must establish a seal between reciprocally movable parts, there is yet another disadvantage. When one of the two parts, between which the cup packing establishes a seal, is shifted with respect to the other part in which the cup packing is seated, then the packing tends to be dragged, due to friction, and is deformed. If the movable part is a shutter that has passage openings which must be open or closed during displacement, then the deformation of the packing modifies the relative positions in which the passage openings are controlled, and if said deformation is excessive it impairs the precision of the shutter's operation and may even actually jeopardize the proper closing, for example, of a faucet.
It has been proposed to rigidify a cup packing by inserting a bushing made of rigid material such as a plastic. However, this procedure has not proven to be sufficiently effective due to the fact that the pressure can be transmitted to the interface between the cup packing and the inserted bushing, and it can thus act on the packing itself causing the above discussed disadvantages.
One purpose of this invention is to provide a cup packing consisting of a relatively yielding elastomeric material which would be able to establish a good seal and which will be able to resist high pressures and pressure surges.
Another purpose of this invention is to provide a cup packing which would be particularly suitable for dynamic operation due to the fact that it does not undergo excessive deformation due to by the displacement of the parts between which the seal is established.
Yet another object of the invention is to provide a cup packing which can be formed with a noncircular cross-section.